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Welcome. If you're returning,

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we're delighted to have you.

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If you're just joining us for the first time,

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we're also glad that you're with us.

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At this point, we're assuming that you're comfortable with functions, with dictionaries,

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you can extract data from nested data structures,

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and that you are comfortable with Python's list comprehensions.

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If you're joining us for the first time,

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please make sure to look at the video on

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the Runestone environment because we'll still be using that for much of what we do here.

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I'm Steve Oney.

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I'm Paul Resnick. We're both faculty members

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at the University of Michigan, School of Information.

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In this course, you'll learn about classes.

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Classes are nice because they allow you to combine the methods and data

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that are relevant to some problem into one nice easy-to-use package.

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In fact, classes are so nice that some programming languages like Java,

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require you to use classes in order to use the language at all.

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Python makes classes optional,

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but as you'll find out in this course,

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they can make your code much easier to read and write.

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You'll also learn about Class inheritance.

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Class inheritance allows you to reuse code which

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can make your code a lot more concise and easier to read.

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You'll also learn about test cases in this course.

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It's kind of an advanced topic for an intro programming sequence,

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but we think it's really valuable to get into the habit of writing

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test cases from the very beginning of your programming career.

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A test case is a way of specifying what a function or a class should do.

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If you write some test cases,

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and then you implement your function,

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if it passes the test cases,

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you know that the function is implemented correctly.

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If it doesn't pass, you know you did something wrong with the function.

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You'll also learn how to handle exceptions.

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So, you've probably encountered runtime exceptions before.

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Whenever you encounter a runtime exception.

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So, when you have a variable that doesn't exist,

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when you try to divide by zero.

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Whenever something like that happens,

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then Python just stops running your program,

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and gives you an error message.

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So, we'll learn how to actually handle these kinds of runtime exceptions,

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and give you more control over how Python evaluates your code.

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In the project for this course,

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you'll use what you learned in write a game of "Wheel of Fortune",

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and you're going to use classes to represent the human player,

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and the computer player,

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and you'll use methods to specify how these players can compete against each other.

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Dr. Charles, Chuck Severance,

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will make a cameo to show you how classes and

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inheritance make it easy to implement web programming using the Django framework.

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Like previous courses, we'll mostly have screencasts with code examples,

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but we'll occasionally come on screen in order

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to introduce words of wisdom or to introduce topics.

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I'll offer a few more dad jokes,

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but not too many this time,

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because this course is mostly Steve.

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So let's get started. Bye for now.